Triple-expansion engine



(No Model.) 2 Sheets--Sheet T. M. EDWARDS. 4

TRIPLE EXPANSION ENGINE.

No. 550,491. Patent ed Nov. 26,1895.

- (No Model.) 2 Shets-Sheet '2.

T. M EDWARDS. TRIPLE EXPANSION ENGINE,

No. 550,491. Patented Nov. 26, 1895;

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UNITED STATES PATENT OFFICE.

THOMAS M. EDWARDS, OF NEW LONDON, CONNECTICUT.

TRIPLE-EXPANSION ENGINE.

SPECIFICATION forming part of Letters Patent No. 550,491, dated November 26, 1895.

Application filed February 19, 1894. Serial No. 500,700. (No model.)

To aZZ whom it may concern.-

Be it known that I, THOMAS M. EDWARDS, a citizen of the United States, residing in the city and county of New London and State of Connecticut, have invented certain new and useful Improvements in Triple Expansion Engines, which improvements are fully set forth and described in the following specification, reference being had to the accompanying two sheets of drawings, in which- Figure 1 is a plan view of the cylinders of an engine embodying my invention; and Fig. 2 is a vertical sectional view of the same,taken on line a? 00. Fig. 3 is a similar sectional view on line y 'y. Fig. 3 is a transverse sectional view taken on the line a a of Figs. 2 and 3, looking in the direction of the arrow. Fig. 4 is a plan view of a modified form of my invention, and Fig. 5 a vertical sectional view of the same on line zz. This figure also shows aportion of the crank-shaft in proper position relative to the cylinders and piston-rods.

My invention is in triple-expansion engines of the marine type, and my immediate object is to produce a novel arrangement of cylinders, steam-valves, and ports, whereby great economy in the use of steam shall be assured. In carrying my said invention into effect, it will be noted that I have preferably located the high-pressure cylinder between the two companion cylinders, and Ihave so arranged the various ports, ducts, and valves that the steam, after having served its purpose in one cylinder, is conducted by the shortest possible and most direct course to the next cylinder of the series, one of my objects being to utilize the steam before appreciable conden= sation sets in, or, in other words, while in its dry condition. I

Referring to the drawings, A, B, and C denote the three cylinders in the order of their arrangement to take steam, and which I shall call the high-pressure, intermediate, and low pressure cylinders, respectively, and the letters a, b, and 0 indicate their respective pistons. a, b, and 0' denote their piston-rods, which may be connected to a crank-shaft D in the usual or any other desired manner,such connections forming, how ever, no part of my present invention.

The high-pressure cylinder A, it will be noticed, is formed with central walls a which in effect provides two end-to-end cylinders, whose pistons are carried by the same rod 'a and which shortens the stroke to conform to that of the other two cylinders. The duplex high-pressure cylinder thus provided (unlike its companion cylinders) takes steam only at one side of each piston, its upper piston being acted upon to produce the upstroke and the lower or companion piston being acted upon to produce the downstroke. Between the walls a is an annular space a into which steam is first introduced through the opening marked Steam in Fig. 3.

At one side of cylinder A and connecting with the described annular chamber a is a cylindrical chest a, in which are two sets of cut-off valves a d of piston form, that are carried by a single valve-rod alandare so distributed that they may register and coact with the ports a and a of the duplex cylinder A in manner substantially like ordinary slide-valves; but it should be noted that the valve-pistons a and a are so set that live steam is introduced only to the lower end of the upper chamber and to the upper end of .with the upper portion of the intermediate cylinder B, and about midway the length of the lower chamber A is a similar port 12 that leads into the lower portion of cylinder B. These ports b and b serve as exhaust-ports for both the cylinders A and B,'as I shall describe a little later; but before doing so I wish to call attention to similar port connections 0 that connect the upper and lower cylinders A with the upper and lower ends, respectively, of the low-pressure cylinder C. It may also be stated here that the relative areas of the several cylinders are or should be so proportioned as to utilize to the best advantage the constantly-reducing pressure of the steam.

When the steam under high pressure has been used in the upper cylinder A, it is exhausted through port 1) into the upperportion of cylinder 13, where, under somewhat reduced pressure, it serves to force downward the piston b. In Fig 2 pistons a are shown on the upstroke and the upper cylinder A is just about to exhaust through port 19 to force pisto'n Z) downward. As the steam thus forces the piston Z2 downward, the steam below said piston is allowed to escape through port 19 into the lower portion of the lower cylinder A and thence through ports 0 into the lower portion of the low-pressure cylinder C, whose piston c is thus forced upward. In practice the piston Z ,when at its extreme highest point, as seen in Fig. 2, serves, during the instant its crank is passing over the center, to close the port 12 so that the steam in the upper chamber A may not too suddenly lose its hold on the piston (L by being allowed to expand into cylinder B.

Between the cylinders A and O is a cylindrical valve-chamber (Z, in which are located cut-01f valves (1- and (1 that are carried bya Valve-rod (1. These valves serve to close and open at proper times the ports 0 and c and are so timed in their action that they close said ports during the periods that steam is acting under high pressure upon the pistons a, and open said ports just following such aetion to permit the steam to pass from cylinder B through cylinders A into the low-pressure cylinder 0.

cylinder A,and meanwhile is being exhausted from the lower portion of cylinderBthrough It will thus be seen steam is T first used under high pressure in the upper the lower cylinder A into the low-pressure cyl- I inder C, and is finally exhausted through the ports 0 into the chamber d and outward 5 through a suitable discharge, (indicated by a 1 The next stroke of i the engine introduces steam under high pressure into the lower cylinder A and cuts it off dotted circle in Fig. 2.)

from the upper cylinder A, which latter is then utilized as a conduit or way through which the steam in the upper portion of cylinder B is exhausted into the low-pressure cylinder 0.

Two marked departures in this class of engines may now be called to notice*first, the

use with two other cylinders of a high-pressure cylinder of duplex form, the companion chambers of said duplex cylinder being acted upon alternately byhigh-pressure steam,and, I second, a similar arrangement of cylinders in which the duplex chambers of the highpressure cylinder may be utilized as conduits 3 or receivers through which the steam may pass from the intermediate cylinder to the; low-pressure or last cylinder of the series. It

may be said, further, that ordinary triple-expansion engines are always constructed so there is a certain amount of back-pressure between the cylinders as the steam exhausts from one into the next of the train, and to relieve in some degree this back-pressure, so called, receivers are provided between the cylinders, into which receivers the exhauststeam may first pass. In my new form of engine the upper and lower ends of the duplex cylinder A serve the same purpose in a more simple manner than when independent receivers are thus provided.

Another valuable feature of my improved engine lies in the fact that I am able in an extremely simple and inexpensive way to equalize the pressure on opposite sides of pistons a.

It will be noticed by reference to Fig. 3, that the cut-off a has passed upward far enough to open the port a of the lower chamber of the cylinder A, thus allowing the steam last used to exhaust through said port into the valve-chamber a, and finally through the port a into the lower end of said lower chamber, where it mingles with the exhaust from cylinder B and passes on to cylinder 0. By thus opening a connection or conduit between the opposite ends of the high-pressure cylinders I am able to equalize the pressure be tween the high pressure and intermediate cylinders, and thus overcome the back-pressure, which is universal in this class of engines, so far as I am familiar with them.

In Figs. 4 and 5 I have shown a somewhat different arrangement of cylinders, the highpressure cylinder A being at one end of the train instead of intermediate the other two; but the duplex cylinder A is constructed and is actuated in precisely the same manner as above described. In the arrangement of cylinders shown in said Figs. 4 and 5 cylinder A exhausts immediately into intermediate cylinder B, and the latter exhausts into the low-pressure cylinder C after the manner of ordinary triple-expansion engines.

Having described my invention, I claim- 1. Ina triple expansion engine, the combination, with a high pressure cylinder formed of two end to end chambers, each provided with a piston and ports, of cut oif valves 10- eated and timed to deliver steam alternately to said chambersat one side only of said pistons, the walls of said chambers being each provided with other ports, a low pressure cylinder and an intermediate cylinder adjacent to and communicating with said high pressure cylinders through said ports, and valves for admitting steam from the intermediate cylinder to the low pressure cylinder through the high pressure cylinder chambers when the high pressure piston in the chamber is moving toward the end provided with the out off valve, substantially as set forth.

2. In a triple expansion engine, the combination, with a high pressure cylinder formed of two end to end chambers, each chamber being provided with a port at each end, and a piston, a cut-off valve timed to deliver steam alternately to said chambers at one side only of said pistons, a valve chamber communicating with the ports at the end of each of said chambers, and valves in said valve chambers for closing and opening the communication between the opposite ends of each of said end to end chambers, whereby the exhaust may pass around to the opposite side of the piston head and equalize the pressure,

substantially as set forth.

3. In a triple expansion engine, the combination, with a high pressure cylinder, of an intermediate cylinder, and a low pressure cylinder, pistons in said cylinders, the high pressure cylinder being formed of two end to end chambers, the walls of which are each provided with four openings or ports, two of which communicate with the steam supply and the other two communicate with the intermediate cylinder, and the low pressure cylinder, respectively, and valves for controlling the ports, substantially as set forth.

4. In a triple expansion engine, the combination, with a high pressure cylinder, of an intermediate cylinder and a low pressure cylinder, pistons in said cylinders, the high pressure cylinder being formed of two end to end chambers, the walls of which are each provided with four openings or ports, two of which communicate with the steam outlet and the other two communicate with the intermediate cylinder and the high pressure cylinder respectively a valve chamber between the low pressure cylinder and the high pressure cylinder, valves within said chamber, and valves for controlling the ports of the high pressure cylinder communicating with the steam supply, substantially as set forth.

THOMAS M. EDWARDS. Witnesses:

FRANK H. ALLEN, LILA D. PEALE. 

